Background. The basic mechanism of delayed cerebral vasospasm following subarachnoid haemorrhage... more Background. The basic mechanism of delayed cerebral vasospasm following subarachnoid haemorrhage (SAH) has been intensively investigated. It is thought that nitric oxide (NO) is a basic mediator of the cerebral vasodilator mechanism. Previous clinical and experimental studies have shown a cerebral vasodilator effect of high cervical spinal cord stimulation (SCS) however, the mechanism of this effect is still controversial. We investigated the contribution of the vasodilator effect of NO to this mechanism in an experimental SAH model using rabbits. Method. Four experimental groups, were designated: Group 1. Cerebral blood flow (CBF) was evaluated by transcranial Doppler ultrasonography (TDU) in 8 rabbits. Group 2. In 4 animals, intracisternal saline injection and cervical epidural electrode placement without SCS were performed before TDU. Group 3. TDU was performed before and after SCS on the fourth day of SAH in 8 rabbits. Group 4. In 8 animals, N-Nitro-L-Arginine Methyl Esther (L-NAME) was administered intracisternally on the fourth day of SAH, at a dose of 0.6 mg/kg, 45 minutes before SCS. CBF parameters, obtained via measurements or calculations from TDU data, were compared. Findings. The occurrence of vasospasm after SAH was demonstrated with significant changes in TDU parameters (high peak systolic velocity and positive values of the degree of stenosis). In all SAH animals, SCS resulted in significant vasodilation. Even after the injection of L-NAME, SCS still had a significant vasodilatory effect in SAH animals, but there was also a significant difference in CBF parameters in the SCS-only group when compared with the L-NAME treatment before SCS group. Interpretation. The mechanism of the cerebral vasodilatory effect of SCS remains controversial. Our results revealed the contribution of a neurohumoral effect which can be partially prevented by use of an NO synthase inhibitor.
In this work, the effects of sodium borohydride concentration on the performance of direct borohy... more In this work, the effects of sodium borohydride concentration on the performance of direct borohydride fuel cell, which consisted of Pd/C anode, Pt/C cathode and Na+ form Nafion® membrane as the electrolyte, have been investigated in steady state/steady-flow and ...
The reaction of (E)-(2-oxo-1,2-dihydroindol-3-ylidene)acetic acid esters with dry acetone at 70°C... more The reaction of (E)-(2-oxo-1,2-dihydroindol-3-ylidene)acetic acid esters with dry acetone at 70°C in presence of aluminum oxide as a catalyst led to the formation of an addition product as a mixture of two isomers. When the same reaction was carried out in presence of morpholine as a base, the unexpected spiro-product was obtained beside the two isomers. Methylation of the latter with methyl iodide in acetone in presence of anhydrous potassium carbonate yielded the corresponding methylated products, whereas methylation of the starting material by the same procedure gave an N-methylated product and the unexpected dispiro-compound. The reaction mechanisms are considered and the structural assignments of the new compounds are based on the chemical and spectroscopic evidences. The structure of the dispiro-product was derived by X-ray analysis.
Infective endocarditis (IE) is an uncommon but life-threatening infection during pregnancy. Altho... more Infective endocarditis (IE) is an uncommon but life-threatening infection during pregnancy. Although there have been several reports of endocarditis caused by Salmonella typhi, to our knowledge it has not been reported as a cause of endocarditis during pregnancy. We report a case of 27-year-old pregnant woman with aortic valve IE caused by S. typhi, who had moderate mitral stenosis and aortic regurgitation. During pregnancy, fever, increase in sedimentation should always alert the physician about the possibility of IE, especially in the presence of predisposing clinical conditions. Whenever possible, transesophageal echocardiographic evaluation should be performed because transthoracic echocardiography might not always demonstrate vegetation as in the present case.
Three new substituted 4-(alkylaminoisonitrosoacetyl)biphenyls (ligands) derived from 4-biphenylhy... more Three new substituted 4-(alkylaminoisonitrosoacetyl)biphenyls (ligands) derived from 4-biphenylhydroxymoyl chloride and corresponding amines were synthesized. The following aromatic and aliphatic amines were used for ligands: ethanolamine, 2-amino-4-methylphenol, and 2-(aminomethyl)pyridine. Mononuclear or binuclear cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), and lead(II) complexes with these ligands were synthesized. These compounds were characterized by elemental analyses, AAS, infrared spectra, and magnetic susceptibility measurements. The ligands were additionally characterized by 1H NMR. The results suggest that the ligands act as tridentate ligands.
In this paper, the design of a speech-controlled wheelchair is presented. The main motivation for... more In this paper, the design of a speech-controlled wheelchair is presented. The main motivation for this design came through the feedback from personal experiences of several colleagues as well as rehabilitation centers of the local hospitals that many elderly patients are unable to use the electronic wheelchairs. This is primarily due to the fact that the types of illnesses common in this group of patients render damages to the motor system of the body affecting mostly arms and feet. Hence, using a joystick type control of an electronic wheelchair is almost impossible. It was however noticed that the speech remains mostly un-altered for these patients and hence it is used in this work to be the main controlling agent for the motion of the wheelchair. However, the speech is not always very clear, specifically in a noisy environment. This brings Fuzzy Logic into the picture which tries to emphasize on the behavioral nature of various commands given to the chair rather than specific sense signal.
Background. The basic mechanism of delayed cerebral vasospasm following subarachnoid haemorrhage... more Background. The basic mechanism of delayed cerebral vasospasm following subarachnoid haemorrhage (SAH) has been intensively investigated. It is thought that nitric oxide (NO) is a basic mediator of the cerebral vasodilator mechanism. Previous clinical and experimental studies have shown a cerebral vasodilator effect of high cervical spinal cord stimulation (SCS) however, the mechanism of this effect is still controversial. We investigated the contribution of the vasodilator effect of NO to this mechanism in an experimental SAH model using rabbits. Method. Four experimental groups, were designated: Group 1. Cerebral blood flow (CBF) was evaluated by transcranial Doppler ultrasonography (TDU) in 8 rabbits. Group 2. In 4 animals, intracisternal saline injection and cervical epidural electrode placement without SCS were performed before TDU. Group 3. TDU was performed before and after SCS on the fourth day of SAH in 8 rabbits. Group 4. In 8 animals, N-Nitro-L-Arginine Methyl Esther (L-NAME) was administered intracisternally on the fourth day of SAH, at a dose of 0.6 mg/kg, 45 minutes before SCS. CBF parameters, obtained via measurements or calculations from TDU data, were compared. Findings. The occurrence of vasospasm after SAH was demonstrated with significant changes in TDU parameters (high peak systolic velocity and positive values of the degree of stenosis). In all SAH animals, SCS resulted in significant vasodilation. Even after the injection of L-NAME, SCS still had a significant vasodilatory effect in SAH animals, but there was also a significant difference in CBF parameters in the SCS-only group when compared with the L-NAME treatment before SCS group. Interpretation. The mechanism of the cerebral vasodilatory effect of SCS remains controversial. Our results revealed the contribution of a neurohumoral effect which can be partially prevented by use of an NO synthase inhibitor.
In this work, the effects of sodium borohydride concentration on the performance of direct borohy... more In this work, the effects of sodium borohydride concentration on the performance of direct borohydride fuel cell, which consisted of Pd/C anode, Pt/C cathode and Na+ form Nafion® membrane as the electrolyte, have been investigated in steady state/steady-flow and ...
The reaction of (E)-(2-oxo-1,2-dihydroindol-3-ylidene)acetic acid esters with dry acetone at 70°C... more The reaction of (E)-(2-oxo-1,2-dihydroindol-3-ylidene)acetic acid esters with dry acetone at 70°C in presence of aluminum oxide as a catalyst led to the formation of an addition product as a mixture of two isomers. When the same reaction was carried out in presence of morpholine as a base, the unexpected spiro-product was obtained beside the two isomers. Methylation of the latter with methyl iodide in acetone in presence of anhydrous potassium carbonate yielded the corresponding methylated products, whereas methylation of the starting material by the same procedure gave an N-methylated product and the unexpected dispiro-compound. The reaction mechanisms are considered and the structural assignments of the new compounds are based on the chemical and spectroscopic evidences. The structure of the dispiro-product was derived by X-ray analysis.
Infective endocarditis (IE) is an uncommon but life-threatening infection during pregnancy. Altho... more Infective endocarditis (IE) is an uncommon but life-threatening infection during pregnancy. Although there have been several reports of endocarditis caused by Salmonella typhi, to our knowledge it has not been reported as a cause of endocarditis during pregnancy. We report a case of 27-year-old pregnant woman with aortic valve IE caused by S. typhi, who had moderate mitral stenosis and aortic regurgitation. During pregnancy, fever, increase in sedimentation should always alert the physician about the possibility of IE, especially in the presence of predisposing clinical conditions. Whenever possible, transesophageal echocardiographic evaluation should be performed because transthoracic echocardiography might not always demonstrate vegetation as in the present case.
Three new substituted 4-(alkylaminoisonitrosoacetyl)biphenyls (ligands) derived from 4-biphenylhy... more Three new substituted 4-(alkylaminoisonitrosoacetyl)biphenyls (ligands) derived from 4-biphenylhydroxymoyl chloride and corresponding amines were synthesized. The following aromatic and aliphatic amines were used for ligands: ethanolamine, 2-amino-4-methylphenol, and 2-(aminomethyl)pyridine. Mononuclear or binuclear cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), and lead(II) complexes with these ligands were synthesized. These compounds were characterized by elemental analyses, AAS, infrared spectra, and magnetic susceptibility measurements. The ligands were additionally characterized by 1H NMR. The results suggest that the ligands act as tridentate ligands.
In this paper, the design of a speech-controlled wheelchair is presented. The main motivation for... more In this paper, the design of a speech-controlled wheelchair is presented. The main motivation for this design came through the feedback from personal experiences of several colleagues as well as rehabilitation centers of the local hospitals that many elderly patients are unable to use the electronic wheelchairs. This is primarily due to the fact that the types of illnesses common in this group of patients render damages to the motor system of the body affecting mostly arms and feet. Hence, using a joystick type control of an electronic wheelchair is almost impossible. It was however noticed that the speech remains mostly un-altered for these patients and hence it is used in this work to be the main controlling agent for the motion of the wheelchair. However, the speech is not always very clear, specifically in a noisy environment. This brings Fuzzy Logic into the picture which tries to emphasize on the behavioral nature of various commands given to the chair rather than specific sense signal.
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